Generating AWS Signature v4 to upload to s3

Ok so I'm trying to create aws v4 signature using this template from Amazon in javascript, with node.js. I am using template credentials, realm, date and service to test my signature function.

I am using the following format to create my signature: Image Link

My StringToSign is a base64 encoded POST policy from template:

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

      

        
        
        
      

    

And my signing key is generated using the following code obtained from the amazon signature v4 key derivation template

var crypto = require("crypto-js");

function getSignatureKey(Crypto, key, dateStamp, regionName, serviceName) {
var kDate = Crypto.HmacSHA256(dateStamp, "AWS4" + key);
var kRegion = Crypto.HmacSHA256(regionName, kDate);
var kService = Crypto.HmacSHA256(serviceName, kRegion);
var kSigning = Crypto.HmacSHA256("aws4_request", kService);
return kSigning;
}

      

        
        
        
      

    

My Key is the SecretAccessKey from the template linked above (WJalrXUtnFEMI / K7MDENG / bPxRfiCYEXAMPLEKEY), my date is "20151229", my region is "us-east-1", and my service name is "s3"

And finally, to get the output, I use

var signature = cryptojs.HmacSHA256(stringToSign, signingKey).toString()

      

        
        
        
      

    

Expected calculation result:

46503978d3596de22955b4b18d6dfb1d54e8c5958727d5bdcd02cc1119c60fc9

      

        
        
        
      

    

But the output I get is:

8afdbf4008c03f22c2cd3cdb72e4afbb1f6a588f3255ac628749a66d7f09699e

      

        
        
        
      

    

If you see where I went wrong, please let me know as I think I followed the amazon template but it seems that I made a mistake somewhere